The Nightosphere is an alternate dimension inhabited by Hana Abadeer and a multitude of other demonic and "deathless" entities. Though initially the only clue as to the appearance of the Nightosphere is that the portal between it and Aaa formed in Marshall Lee's House led to a place engulfed in fire, where it was viewed to be a demonic wasteland filled with chaos and many unhappy and unsatisfied demons.
It would be impossible to send The Lichress to the Nightosphere because she's not from that universe.
"Maloso vobiscum et cum spiritum" roughly translates from Latin to: "Evil be with you and with your spirit."
Due to its fiery atmosphere the Nightosphere appears similar to the Fire Kingdom.
The Nightosphere has a demon jail only to maintain the illusion of order.
The name "Nightosphere" could be a play on the word "lithosphere " which is used to describe the outer rock layers of planet Earth. The word "lithosphere" contains the past tense of the verb "to light." Because the Nightosphere is an alternate dimension to the Land of Aaa and namely Earth, the hypothetical and comical opposite of "lithosphere" with light, would be "Nightosphere" with night.